package JDBC;

import java.sql.*;

public class Example01 {
    public static void main (String[] args) throws SQLException {
        /** JDBC连接数据库
         * 1.加载 驱动
         * 2.链接
         * 3.表结构
         * 4.预处理(SQL)
         * 5.结果
         * 6.释放 链接
         */
        /**
         * (1) 加载
         * a.根目录创建Lib文件夹
         * b.将连接的jar包放入Lib
         * c.点击 文件-<项目结构-<模块-<依赖-<+号-<JAR或目录-<选中mysql的jar包
         * d.编写加载代码
         */
        Statement stmt = null;
        ResultSet rs = null;
        Connection conn = null;
        try {
          // 1.注册数据库的驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            // 2.通过DriverManager获取数据库连接
            String url = "jdbc:mysql://localhost:3306/jdbc?serverTimezone=GMT%2B8&useSSL=false";
            String username = "root";
            String password= "123456";
            conn = DriverManager.getConnection(url, username,password);
            // 3.通过Connection对象获取Statement对象
            stmt=conn.createStatement();
            // 4.使用Statement执行SQL语句。
            String sql = "select * from users";
            System.out.println("id |   name |   password   |  email     |    birthday");
            rs = stmt.executeQuery(sql);
            // 5. 操作ResultSet结果集
            while (rs.next() ) {
                //每轮循环 rs代表一行数据
                int id = rs.getInt("id");//通过列名获取指定字段的值
                String name = rs.getString("name");
                String psw = rs.getString("password");
                String email =  rs.getString("email");
                Date birthday = rs.getDate("birthday");
                System.out.println(id + "  |  " + name + "  |  " + psw + "  |  " + email + "  |  " + birthday);
            }

        }catch (ClassNotFoundException e ) {
            e.printStackTrace();
        } finally {
            // 6.回收数据库资源
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                rs = null;
            }
            if (stmt != null) {
                try {
                    stmt.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                stmt = null;
            }
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                conn = null;
            }
        }
    }
}

